Floating wind turbine systems and methods

This application is a non-provisional of and claims the benefit of U.S. Provisional Application No. 63/276,082, filed Nov. 5, 2021, entitled “SELF-UPENDING FLOATING WIND PLATFORM SYSTEMS AND METHODS.” This application is hereby incorporated herein by reference in its entirety and for all purposes.

This application is a non-provisional of and claims the benefit of U.S. Provisional Application No. 63/276,086, filed Nov. 5, 2021, entitled “DOWNWIND FLOATING WIND TURBINE AND ITS CONTROL SYSTEM.” This application is hereby incorporated herein by reference in its entirety and for all purposes.

is first side view of an example embodiment of a floating wind turbine.

is a second side view of the example embodiment of the floating wind turbine of

is first side view of another example embodiment of a floating wind turbine.

is a second side view of the example embodiment of the floating wind turbine of

is a perspective view of a further example embodiment of the hull and tower of a floating wind turbine.

is a side view of a floating wind turbine in a near horizontal or non-vertical configuration.

is a side view of an articulating tug barge with retractable rams in accordance with an embodiment.

is a top perspective view of a rigid arm single point mooring (SPM) buoy system in accordance with an embodiment.

is a perspective view of a nacelle that includes a wind turbine comprising three turbine blades.

illustrates an example embodiment of a self-upending floating wind turbine in an upright (e.g., operational) configuration.

is a close-up view of a lower portion of the floating wind turbine of.

illustrates an example embodiment of a self-upending floating wind turbine in a folded (e.g., transport) configuration.

illustrates an example embodiment of a self-upending floating wind platform during an upending operation.

illustrates another example embodiment of a floating wind turbine that has three outer columns.

illustrates an example of an upwind floating wind turbine where the central axis Y of the tower is at a heel angle of 0° with a rotor tilt angle of 5°.

illustrates the upwind floating wind turbine ofat a heel angle of 10°.

illustrates an example of a downwind floating wind turbine where the central axis Y of the tower is at a heel angle of 0° with a rotor tilt angle of 5°.

illustrates the downwind floating wind turbine ofat a heel angle of 10°.

illustrates an example of a downwind floating wind turbine with a teetering rotor.

is a block diagram of a wind turbine controller method.

illustrates an example embodiment of a downwind floating wind turbine under static conditions with a static tilt angle of 5° and a heel angle of 0° which in this example causes an Annual Energy Production (AEP) reduction of 0.4% compared to a tilt angle of 0°.

illustrates an example embodiment of a passive downwind floating wind turbine under rated thrust conditions with a static tilt angle of 5° at a heel angle of 100 that causes a rotor misalignment of −5°, which in this example causes an AEP reduction of 0.4% compared to a rotor misalignment of 0°.

illustrates an example embodiment of an upwind floating wind turbine under static conditions with a static tilt angle of 5° and a heel angle of 0°, which in this example causes an AEP reduction of 0.4% compared to a tilt angle of 0°.

illustrates an example embodiment of a passive upwind floating wind turbine under rated thrust conditions with a static tilt angle of 5° at a heel angle of 5° that causes a rotor misalignment of 10°, which in this example causes an acceptable AEP reduction of 1.5% compared to a rotor misalignment of 0°.

illustrates an example embodiment of a passive upwind floating wind turbine under rated thrust conditions with a static tilt angle of 5° at a heel angle of 100 that causes a rotor misalignment of 15°, which in this example causes an unacceptable AEP reduction of 3.4% compared to a rotor misalignment of 0°.

It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of the preferred embodiments. The figures do not illustrate every aspect of the described embodiments and do not limit the scope of the present disclosure.

One advantage of deploying some embodiments of floating wind turbines offshore over bottom-fixed wind turbines can be that such floating wind turbines can be assembled and commissioned using onshore cranes and machinery and then towed out to site. However, the access to many ports around the world can be hindered by bridges or other obstacles (e.g., airport regulations) that can constrain the distance a structure rises from the sea level (known as the ‘air draft’). Much of the world's existing infrastructure has been driven by the global shipping industry, which has standardized vessel classes (e.g., PANAMAX, CHINAMAX, etc.). Air draft allowances can be 50-70 m in some examples. Some wind turbines can have hub heights in excess of 100 m, rendering many large ports or shipyards inaccessible.

The present disclosure in one aspect provides systems and methods for accessing these ports by articulating the wind turbine to a horizontal position during transit. Once located in deeper waters, past the obstruction, the turbine can then be upended into an erected configuration. Furthermore, many ports can have draft restrictions that can be as low as 7 m-8 m. By transporting the turbine in a horizontal position, the wind turbine, the draft can be reduced in various embodiments.

Another benefit of some examples discussed herein can be to reduce loading on the wind turbine and floating hull structure in extreme wind or fault events. The turbine tower, in some embodiments, can be forced to articulate to a horizontal (or near horizontal) position either by strong winds or by the inclusion of a motor, actuator, or the like. When the turbine is in such a position, the loads on the turbine and the floating hull can be reduced. During a turbine fault event, the forces from the turbine may not be directly transferred to the hull in some examples. Instead, the energy can be dissipated through the viscous damping of the turbine sub-structure in various embodiments.

Current wind turbines can be robust on land and on fixed offshore wind platforms but their usage on floating platforms typically requires elaborate control systems or large platforms. These platform control systems are costly to install and difficult to maintain and operate as they require regular maintenance. In some wind turbines, the rotor is tilted upward by 4-8 degrees in order to increase the clearance between the blade tips and tower in operation. This angle relative to the horizontal is referred to as the shaft axis, as the main shaft of the wind turbine is from the generator or gearbox to the hub to transmit torque from the rotor.

A wind turbine described in various embodiments of the present disclosure includes a downwind turbine, where the rotor is oriented 4-8 degrees upward from the horizontal in order to increase the clearance between the blade tips and tower in operation. The wind turbine in various examples produces a thrust force in order to produce power from the wind. The thrust force can result in an overturning moment on the platform, which can cause the platform to have a mean heel angle. Here, a heel angle can be the mean pitch angle of the platform, in the direction of the wind.

In some examples of a floating wind platform, the target design heel angle is the heel angle of the platform when it is subject to the rated thrust force of the turbine. Generally, the rated thrust force is the maximum mean thrust force on the turbine during operation. The design heel angle of a platform can depend on the restoring force of the platform and mooring system, which can be a function of its center of gravity and buoyancy, its waterplane moment area of inertia and the restoring force due to the mooring system. In general, increasing the platform's hydrostatic stiffness can result in increased cost or complexity of the system, or both. For instance, for a conventional semi-submersible floating wind platform, the hydrostatic stiffness can be increased by increasing the spacing of the columns, increasing the size of the columns, or both. Wind platforms, without active platform control systems, can target a design heel angle of 4-5 degrees, so that that the maximum rotor misalignment is 8-13 degrees from the horizontal. In various embodiments, the power of the turbine is a function of the swept area of the rotor. The swept area decreases as function of the tilt angle of the turbine as function of the cosine of the tilt angle (gamma). Mathematically,0.5**cos(gamma)*3

Where rho is air density, Cp is power coefficient, A is swept area of blades, gamma is tilt angle of turbine, V is velocity of wind.

Some embodiments include a floating, downwind fixed-hub turbine that passively operates at a mean heel angle. For example, to produce power thrust is produced, and such thrust can cause the platform to tilt (heel) over in the direction of the wind. By designing a floating wind turbine that has a mean heel angle of 10 degrees, for example, then in various embodiments you have the same rotor misalignment as an upwind turbine that is oriented vertically, such as one on land (+/−5 degrees). By designing a platform that has a mean heel angle of 15 degrees, for example, then you have the same rotor misalignment as an upwind turbine on a floating platform with a heel angle of 5 degrees.

Some embodiments include a floating, downwind teetered turbine that passively operates at a mean heel angle. By designing such floating wind turbine that has a mean heel angle of 15 deg, for example, in various embodiments you then can have less rotor misalignment than an upwind turbine that is oriented vertically (e.g., 0 deg vs+5 degrees).

Some wind platforms, with active platform control systems, can target a design heel angle of 5-8 degrees, so that the tower can remain vertical and the maximum rotor misalignment can be maintained at 4-8 degrees. Some wind turbines can have larger active control systems which can cause an increased tilt angle, resulting in 0 degrees rotor misalignment. However, a need exists for an improved floating-specific wind turbine and method for its control in an effort to overcome the aforementioned obstacles and deficiencies of some examples of wind turbine systems.

In various embodiments, a benefit of a tilting, downwind floating wind turbine operating at a tilt angle can be that the wake generated by the floating wind turbine can be driven down and have a reduced effect on the downstream floating wind turbine where a plurality of floating wind turbines are disposed in an array, group or farm. In various embodiments, this can allow more floating wind turbines to be packed into in a given area, which can be a large concern for floating wind turbine operators and other stakeholders (fishing, e.g.).

Below are described example systems and methods, that in accordance with some embodiments, can be used to design lighter, more inexpensive floating wind turbines including towers and supporting hull platforms. For example, various embodiments can include a floating wind turbine comprising one or more of:

One embodiment can be designed so that platform is as shown in. Such a design can comprise, consist essentially of, or consists of one or more of the following elements, with one or more of such elements being specifically absent in some embodiments.

One embodiment comprises, consists essentially of, or consists of a floating downwind turbine with a turbine control system that can be used to optimize the tilt angle of the platform.

Another embodiment comprises, consists essentially of, or consists of a floating downwind turbine with a teetered hub, and a turbine control system that can be used to optimize the teeter angle of the rotor and the tilt angle of the platform.

In some such embodiments, no active control system exists on the platform, as the platform can be allowed to passively pitch or tilt in the direction of the wind. However, in various examples, the turbine is able to produce full power, as the rotor plane can remain aligned with the horizontal.

Turning to, two example embodimentsA,B of a floating wind turbineare illustrated inand inrespectively. The floating wind turbineis shown comprising a tower bodyhaving a tower shaftthat extends along an axis Y. The tower bodyfurther comprises a tower baseat a bottom end of the tower shaft, with a keel platedisposed at a terminal bottom end of the tower body. One or more finscan extend between the keel plateand tower baseto reinforce a coupling between the keel plateand tower baseand/or provide dampening for rotation, movement or pitch of the tower.

A nacellecan be disposed at a top end of the tower body. The nacellecan be configured in various suitable ways and comprise various suitable elements, including a wind turbinecomprising a hubwith a plurality of bladesextending from the hubas shown in the example of. Further embodiments can include any suitable plurality of blades, including 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 24, 36, 48, or the like. In some embodiments, a wind turbinecan operate in a horizontal-axis with and upwind or downwind rotor or can operate in a vertical-axis.

Various embodiments can include any suitable turbine elements, so the example ofshould not be construed as being limiting. Additionally, while various example embodiments herein relate to wind turbines, it should be clear that further embodiments can be employed for various suitable purposes including a light house, bridge, communications array, weather station, observation station, weapon mount, or the like.

Returning to, the floating wind turbineis further shown comprising a hullthat includes a pair of base elementsand a pair of support architectures, which are spaced apart and coupled together via one or more bars. As shown in the examples of, the pair of base elementsA,B, the pair of support architecturesA,B and the one or more bars can define a hull cavity.

A pitch platecan extend between the support architecturesA,B and be rotatably coupled to the hullvia pitch shaft, which allows the pitch plateto rotate about an axis X. The tower shaftand/or tower basecan extend through and be coupled to the pitch plate, which can allow the towerto rotate about the axis X via the pitch plate. In various embodiments, axis Y of the towercan be perpendicular to and/or coincident with the axis X. As shown in the examples of(and alsodiscussed in more detail herein), such rotation of the towervia the pitch platecan allow the tower baseand/or keel plateto swing or pitch within the hull cavityto various configurations as discussed herein.

Additionally, the towercan be coupled to the pitch platevia a yaw bearing, which can allow the tower shaftand/or tower baseto rotate about axis Y of the tower. Providing for rotation of the towerabout the axis Y can be desirable in some embodiments to position the nacellein a desired or optimal direction, such as at an angle where a wind turbineassociated with the towerproduces a maximum amount of energy, produces a maximum amount of energy without compromising structural integrity of the blades, to protect the bladesfrom wind damage, and the like. Additionally, in some embodiments, the nacellecan be rotatably coupled to the top of the towerin addition to or as an alternative to a yaw bearing. In some embodiments (e.g., downwind turbine embodiments), there may be or may not be a yaw motor or actuator that actively drives yaw rotation of the towerabout central axis Y. In some examples, wind turbine weathervanes can be downwind and the yaw bearingcan allow passive rotation of the towerrelative to the hull. In another embodiment, a conical bearing can allow free yaw motion of the tower, while the hullcan be split (e.g., as shown in).